1. Field of the Invention
The present invention relates to a pressure adjustment apparatus provided with a buffer chamber for damping a pulsating flow generated by a pump which adjusts the back pressure in a liquid ejection head, and to an image forming apparatus provided with this pressure adjustment apparatus, a pressure adjustment method for adjusting the back pressure in a liquid ejection head, and a liquid remaining amount determination method which is based on the adjustment of back pressure in a liquid ejection head.
2. Description of the Related Art
An inkjet printer has been known which includes a plurality of nozzles which eject ink, a plurality of pressure chambers which are connected respectively to the plurality of nozzles, and a common flow channel for supplying ink to the plurality of pressure chambers. In the liquid ejection head of this kind, in order to avoid leakage of ink from the nozzles, it is necessary to set the pressure in the flow channels inside the liquid ejection head (and more specifically, the pressure inside the pressure chambers and the pressure inside the common flow channel) to a pressure that is lower than the atmospheric pressure. Moreover, if the pressure in the flow channels inside the liquid ejection head varies, then this affects the liquid droplet generating process, which in turn affects the quality of the image formed on the ejection receiving medium. Therefore, it is preferable to maintain a uniform pressure differential between the pressure in the flow channels of the liquid ejection head, and the atmospheric pressure.
Japanese Patent Application Publication No. 2006-150963 discloses a durable and relatively simple pressure adjustment apparatus for adjusting the pressure in the flow channels inside a liquid ejection head in which a membrane pump for pressure adjustment is provided, and a buffer tank for reducing the pulsating flow generated by the pump is provided in the ink tube between this pump and the liquid ejection head.
However, since the buffer tank provided in the ink tube between the pump and the liquid ejection head generally has a large volume, then it takes time until the pressure inside the liquid ejection head reaches a prescribed negative pressure which is lower than the atmospheric pressure. If it takes time to establish the back pressure (a negative pressure which is lower than the atmospheric pressure) in the liquid ejection head in this way, then the standby time until the start of a printing operation becomes longer, and therefore the printing productivity declines.